The SAXON package is a collection of tools for processing XML documents. The main components are:

* An XSLT processor, which implements the Version 1.0 XSLT and XPath
Recommendations from the World Wide Web Consortium, found at
http://www.w3.org/TR/1999/REC-xslt-19991116 and
http://www.w3.org/TR/1999/REC-xpath-19991116 with a number of
powerful extensions. This version of Saxon also includes many of
the new features defined in the XSLT 1.1 working draft, but for
conformance and portability reasons these are not available if
the stylesheet header specifies version="1.0".

* A Java library, which supports a similar processing model to XSL,
but allows full programming capability, which you need if you
want to perform complex processing of the data or to access
external services such as a relational database

* A slightly improved version of the Aelfred parser from Microstar.
(But you can use SAXON with any SAX-compliant XML parser if you
prefer).

So you can use SAXON by writing XSLT stylesheets, by writing Java applications, or by any combination of the two.